Litvin and co-workers (Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, 4, pp. 854-857, April, 1973) hydrogenated 1,3- and 1,4-phenylenediamine in various solvents at 120° C., 1175 psia, in the presence of supported Ru and Rh catalysts.
U.S. Pat. No. 4,181,680 relates to a process for hydrogenation of an aromatic bis-methylamine at 50° to 150° C., 500 to 2000 psig, in water and the presence of a supported ruthenium catalyst and in the absence of added ammonia.
U.S. Pat. No. 5,360,934 relates to a catalytic hydrogenation process for conversion of aromatic amines to ring hydrogenated compounds in which the catalyst is rhodium on a kappa alumina support.
U.S. Pat. No. 5,981,801 relates to a method for preparation of cycloaliphatic diamines by hydrogenation of the aromatic diamine in the presence of an air or oxygen pre-treated ruthenium catalyst.
JP Patent No. 59216852, May 23, 1983, Nippon Kayaku Co., Ltd. relates to a hydrogenation process for production of aliphatic diamines from the corresponding aromatic diamines by use of a supported rhodium catalyst in water and in the presence of sodium or potassium phosphate and ammonia, a secondary alkylamine, or a tertiary alkylamine.
H. C. Brown and C. A. Brown, JACS, 84, 1494-1495 (1962) disclose the preparation of highly active platinum metal catalysts by the treatment of solutions of platinum metal salts with aqueous sodium borohydride. These catalysts were not prepared on supports such as carbon.
U.S. Pat. No. 3,869,521 claims a catalytic hydrogenation process for conversion of alkylbenzene compounds to the corresponding cyclohexane by using a supported transition metal catalyst prepared by impregnating a support with a solution of a transition metal salt and reducing the transition metal salt in-situ using a sodium borohydride solution.
It would be desirable to provide an improved method for the synthesis of 1,2-diaminocyclohexane that operates at low to moderate pressures to provide commercially useful yield and conversion.